In essence there seems to be a need for laws that are most effective, rather than those you'd want in an ideal society. Divorce seems to be something you're told in the Bible not to do yet at the same time even the theocratic state of ancient Israel gave specific rules by which men could initiate divorce. This seems to me to be a probable source of inspiration for the views of Augustine and Thomas Aquinas on prostitution. Here's what they had to say:

At the same point in time, New Zealand and parts of Australia also legalized prostitution and the governments of those two countries seem to be reporting better results. e.g. in New Zealand the government reported that:

the Prostitution Reform Act (PRA) 2003 has had a positive effect on the health and safety of sex workers and has not led to a predicted increase in their numbers.

... reforms that decriminalised adult sex work have improved human rights; removed police corruption; netted savings for the criminal justice system; and enhanced the surveillance, health promotion, and safety of the NSW sex industry. ... Contrary to early concerns the NSW sex industry has not increased in size or visibility, and sex work remains stigmatized.

I previously mentioned some research arguing that legalized prostitution increased human trafficking, yet at the same time New Zealand reported no connection between legalization and trafficking and the report evaluating legalization in New South Wales actually reported a drop in detectable human trafficking. What might explain the differences between what's been observed in those countries in Europe which legalized prostitution and the different effects it seems to have had in Oceania?

New legislation on prostitution is something to be expected in Canada not too far in the future. It seems likely that Canada will either move to an approach wherein prostitution is legalized, or it will move to the "Nordic Model" wherein the selling of sex is legal but the buying of it is criminalized.

Not too surprisingly, where purchasing sex is illegal the sex trade isn't quite as visible. The question though is whether or to what extent that's as a result of a decrease in prostitution or if it just continues underground wherein you might expect the prostitutes to fair worse. The police in Sweden seem to be detecting underground human trafficking rings involving forced prostitution and a study in Norway concluded that criminalizing the purchase of sex resulted in pimps having greater control over prostitutes and lead to increased human trafficking. How that compares to what might have transpired had they come up with this Nordic Model is the question.

The case of Elliot Rodgers also comes to mind when evaluating the "Nordic Model" as the same article noting growing negative views on prostitution also found that criminalizing prostitution was correlated with a slight increase in reported rapes and sexual assaults in Sweden. There is of course the perennial question of correlation versus causation. If sex is argued to be irresistible by those creating current sex education programs in schools, does an argument in a similar vein mean legal prostitution?

At the moment both legalization and the Nordic model have their advocates. At the moment an alphabet soup of UN-affiliated organizations also appears to be advocating legalized prostitution as the least terrible option and the EU parliament is promoting that Nordic Model. If I had to bet on what Canadian politicians will opt to do I suspect the Nordic model is the more likely of the two to be finding its way into the Canadian Criminal Code sometime soon. It seems to me to be the easier sell from a political standpoint but whether it's really the least terrible option is a different question. That's one that I'm not sure I know the answer to.

(One other issue that I haven't really seen discussed much is that of consistency with other laws. i.e. If a woman's right to bodily autonomy is deemed by Canadian law to justify ending a human life it seems tough to argue in a consistent manner that that same woman's same right to bodily autonomy wouldn't also justify engaging in a mere financial transaction. It sort of seems like saying that if someone steps foot on your property you're allowed to shoot to kill but not to, e.g., sell them lemonade from your lemonade stand).